Labour says it will repeal the controversial GCSB law if it wins the next election.

A Labour spokesman confirmed this afternoon the party would commission a review of the legislation and implement any changes that came out of that although the new law would remain in place until that process was completed.

The comments come following a meeting in Auckland last night attended by a number of prominent New Zealanders including New Zealander of the Year Dame Anne Salmond and retired Court of Appeal Judge Ted Thomas as well as internet entrepreneur Kim Dotcom.

"The situation is at is has always been - Labour has committed to, when it gets in Government, to having a full and independent enquiry into the intelligence services . . . and any changes will flow out of that," the spokesman said.

"There's no suggestion that Labour would get into Government and repeal it and then have a vacuum while it sorted out the enquiry. You're not going to repeal it and not replace it with something."

The review would take a matter of months, he said.

About 400 people attended the meeting in Mt Albert last night ahead of nationwide protests planned for tomorrow.

At the meeting, Salmond denounced politicians and said they "need to grow a backbone" rather than consider passing a spy bill which she said had been "universally condemned" by the public.

New Zealanders ought to feel "very concerned" about the bill, she said.

"This agency . . . is surrounded by scandal - it has been accused of carrying out illegal surveillance on New Zealand citizens," she said.

"This bill allows the GCSB to illegally spy on New Zealanders.

"This bill is in breach of the Bill of Rights . . . and despite this it has been dealt with under urgency.

"All of the authorities have looked at this carefully and have argued this bill be shelved."

Salmond said the bill would be an "absolute indictment" of the Government if it was passed.

Rodney Harrison QC who said he was speaking in a personal capacity and not on behalf of the New Zealand Law Society, said he agreed that MPs needed to "grow some backbone".

"If you are going to increase the powers of the GCSB you have to apply much greater scrutiny because most of what they do will never come to public attention," he said.

"Legislation dealing with their powers has to be carefully and tightly drawn. This legislation is not. It is hopelessly broad."

Harrison said "most of us" were "totally ignorant about the methods that are being used by the GCSB".

"History tells us that once enforcement agencies and spy agencies are clothed with power it is never taken away from them, it is only ever increased," he said.